纳米CaSiO₃发光材料的性能及特殊形貌研究

【作者】 方敏；

【导师】 杨良准；

【作者基本信息】 上海师范大学 ， 应用化学， 2007， 硕士

【摘要】 基于CaSiO₃:Pb,Mn的实际应用价值,而目前生产上多采用高温固相法,产物具有粒径较大且发光强度不高等缺点,本文研究了CaSiO₃:Pb,Mn的其它制备方法。同时采用反胶束法,探索了制备具有特殊形貌的新型CaSiO₃:Eu³⁺纳米荧光粉材料的方法。通过荧光光谱、XRD、TEM、SEM、FTIR、DTA-TG等手段对材料进行测试,探讨了不同实验条件和方法对材料荧光性能及形貌的影响。第一部分采用溶胶-凝胶法并辅以超声技术制备了CaSiO₃:Pb,Mn发光材料,研究了制备时的物料配比、超声时间及焙烧温度对样品发光强度的影响,找到了最佳的合成条件。结果表明,所得样品其荧光强度约为高温固相法样品的2倍,平均粒径则降低约300 nm。第二部分采用溶胶凝胶法制备了CaSiO₃:Pb,Mn荧光粉,结果表明,在溶胶过程中分别加入三种非离子型表面活性剂ON70、TO8和XL80后,样品荧光强度均增强,以XL80的效果为最佳。当V（XL80）:V（溶胶）的体积比为0.5:50时,所得样品荧光强度约为高温固相法样品的3倍,且粒子分散性好,选区电子衍射图出现单晶点阵排列,纳米晶平均粒径约150nm;当V（XL80）:V（溶胶）为1:50时,荧光粉粒子形貌呈现长短、宽窄不一的纳米棒状,电子衍射图呈现更规则有序的单晶点阵。第三部分采用溶胶-凝胶法制备了CaSiO₃:Pb,Mn,Li发光材料,研究发现,随着Li+的掺入量的增大,CaSiO₃:Pb,Mn的合成温度显著降低,发光强度增大,并发生一定蓝移。当Li+的掺入量为0.65%时,CaSiO₃:Pb,Mn,Li的合成温度降至900℃,Mn²⁺的发光强度增大3倍左右,发射主峰由650nm蓝移至615nm附近。最后采用反胶束法制备了CaSiO₃: Eu³⁺纳米材料,研究得知,当w0值为5,XL80/环己烷浓度为0.2mol/L时可以得到粒径较均一的球形荧光粉。同时研究了焙烧温度对CaSiO₃:1%Eu³⁺形貌及结晶度的影响。结果显示其晶化温度（668℃）和相变温度（790℃）与体材料相比都有明显减小。CaSiO₃:1%Eu³⁺样品在70℃烘干后可以得到平均粒径在100nm以下粘合在一起的纳米球,当700℃焙烧后得到粒径为350nm左右的均一纳米球,当焙烧温度达到800℃时球体几乎全部破裂熔融。文中还研究了不同Eu³⁺掺杂浓度对样品形貌及荧光性能的影响,结果发现,随着Eu³⁺掺杂量的不断增加,粒径趋于非均一化,且粒径变大,当摩尔掺杂浓度达到6%时,球形大部分被破坏。通过荧光光谱显示,在395nm激发下得到敏感跃迁5D0→7F2的613nm处红光发射,表明Eu³⁺更倾向于占据非反演中心的格位,且摩尔掺杂浓度达到5%时荧光强度仍未减小,表明此方法制备的纳米球的猝灭浓度大于高温固相法制备的体材料的猝灭浓度。更多还原

【Abstract】 Based on the practical value of CaSiO₃: Pb, Mn, and at present the sample is almost made by the high temperature solid-state reaction, but the particle size is big and the luminescence is not strong. In this paper, other preparation method has been studied, and CaSiO₃:Eu³⁺ luminescence nanomaterials with special surface morphology have also been prepared from the reverse micelle micelles. The influence of different methods and conditions on the luminescence and surface morphology have been characterized by Luminescence spectrum, XRD、TEM、SEM、FTIR and DTA-TG.The first part studied that the luminous materials of CaSiO₃: Pb, Mn were synthesized by Sol-gel method and ultrasound technology. Effects of factors such as the synthetic material compositions, ultrasound time and annealed temperature on phosphorescent brightness of sample were studied and the optimum synthetic conditions were determined. The results show that, compared with the sample made by the high temperature solid-state reaction, the luminescent intensity of the CaSiO₃: Pb, Mn sample increased by about 200% and the mean diameter of particles of the sample decreased by about 300nm.The second part was that the luminous materials of CaSiO₃: Pb, Mn were synthesized by Sol-gel method. The results indicated that the luminescent intensity of all the samples were enhanced when three kinds of nonionic surfactants ON70、TO8 and XL80 were added respectively in sol process and the addition of XL80 showed the best enhancement in luminescent intensity. When the V（XL80）:V（sol）was 0.5:50, the luminescent intensity of the CaSiO₃: Pb, Mn sample was three times of that of the sample made by the high temperature solid-state reaction, and the dispersivity of the particles was also rather better. The figure of selective area electron diffraction （SAED） showed single crystal lattice, the mean diameter of nanocrystals was about 150nm. When the V（XL80）:V（sol）was 1: 50, the particles of phosphors were synthesized as nanorods with different length and width, and the figure of SAED showed more orderly single crystal lattice.The third part was that a series of luminescent materials, CaSiO₃: Pb, Mn, Li, were synthesized by Sol-Gel method. It is found that the little addition of Li+ ions results in decreasing synthesizing temperature, increasing emission intensity of Mn²⁺ ions and blue shift of its emission band. When the doping amount of Li+ ion in CaSiO₃: Pb, Mn is 0.65%, the synthesizing temperature of CaSiO₃:Pb,Mn decreased to 900°C, its emission intensity increased about three times, and its emission shift from 650nm to around 615nm.At last, we researched CaSiO₃:Eu³⁺ nanospheres prepared from the reverse micelle micelles consist of Lutensol XL80, cyclohexane and water. The results show that, the uniform nanospheres were prepared while the w0 value is 5 and the concentration of XL80/cyclohexane is 0.2mol/L. The influence of the sintering temperatures on the shape and crystallization of CaSiO₃:1%Eu³⁺ phosphor was investigated. The results showed that the temperature of crystallization （at 668℃） and phase transition （at 790℃） of CaSiO₃:1%Eu³⁺ nanospheres decreased compared with bulk materials. The average size of CaSiO₃:1%Eu³⁺ agglutinated nanospheres drying at 70℃was below 100nm, and the uniform nanospheres with the average size of 350nm was prepared while annealed at 700℃. Further annealed at 800℃, the nanospheres almost breaked and melted down. The effect of CaSiO₃ doped with different concentration of Eu³⁺ on the shape and photoluminescence was also studied. The uniform nanospheres morphology was destroyed with the increasing concentration of Eu³⁺, and the particle size was increased. As doping 6% Eu³⁺, the particles presented anomalistic morphology. The main emission band excited at 395nm was the hypersensitive 5D0→7F2 red emission at 613nm. It showed that Eu³⁺ ions are located in more non-reversion center lattices. As doping 5% Eu³⁺, the emission intensity still have not been reduced, which indicated that the prepared nanospheres had much higher quenching concentration than that of bulk materials which were made by the high temperature solid-state reaction.更多还原